Gotta re-state what has already been stated....If you have an automatic transfer switch (ATS) it's "SUPPOSED" to keep any conflict between shore power and generator power de-conflicted....but there's always that chance. It doesn't take that much effort to turn everything off inside the coach, flip off the shore-breaker or unplug the shore power before starting the genset. Just a protective measure to make sure there's not problem. My $.02 worth and it's probably worth less than you paid for it! ;-)